Shape memory epoxies based on networks with chemical and physical crosslinks

Leonardi, Agustina Belen; Fasce, Laura Alejandra; Zucchi, Ileana Alicia; Hoppe, Cristina Elena; Soulé, Ezequiel Rodolfo; Pérez, Claudio Javier; Williams, Roberto J. J.

doi:10.1016/j.eurpolymj.2010.12.009

Cited by 114 publications

(92 citation statements)

References 27 publications

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“…Overall, it should be pointed out the mechanical performance of these materials, in terms of σb and εb, they are superior to other epoxy-based SMPs. Williams et al [14] reported an epoxy-amine system (based on a long aliphatic chain n-dodecylamine) with large tensile elongations (up to 75%) and high recovered stresses (over 4 MPa), when programming at a temperature close to the Tg. Rousseau et al [10] reported epoxy-amine systems (based on long flexible polyetheramines) with Overall, it should be pointed out the mechanical performance of these materials, in terms of σ b and ε b , they are superior to other epoxy-based SMPs.…”

Section: Mechanical Analysis: Influence Of the Network Structure And mentioning

confidence: 99%

“…To this end, very few works have focused on the study of the relation between the network structure and, either the strength or the shape-recovery process. Williams et al [14] improved the tensile strain of an epoxy-based system and reported a great strength by combining chemical and physical crosslinking through a long aliphatic chain (n-dodecylamine) and a compact rigid structure (m-xylylenediamine). Our group developed hyperbranched poly(ethyleneimine)-modified epoxy SMPs with enhanced ultimate strength (up to 12 MPa of stress at break), maintaining high ultimate strain [15].…”

Section: Introductionmentioning

confidence: 99%

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Effect of the Network Structure and Programming Temperature on the Shape-Memory Response of Thiol-Epoxy “Click” Systems

et al. 2015

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This paper presents a new methodology to develop "thiol-epoxy" shape-memory polymers (SMPs) with enhanced mechanical properties in a simple and efficient manner via "click" chemistry by using thermal latent initiators. The shape-memory response (SMR), defined by the mechanical capabilities of the SMP (high ultimate strength and strain), the shape-fixation and the recovery of the original shape (shape-recovery), was analyzed on thiol-epoxy systems by varying the network structure and programming temperature. The glass transition temperature (T g ) and crosslinking density were modified using 3-or 4-functional thiol curing agents and different amounts of a rigid triglycidyl isocyanurate compound. The relationship between the thermo-mechanical properties, network structure and the SMR was evidenced by means of qualitative and quantitative analysis. The influence of the programming temperature (T prog ) on the SMR was also analyzed in detail. The results demonstrate the possibility of tailoring SMPs with enhanced mechanical capabilities and excellent SMR, and intend to provide a better insight into the relationship between the network structure properties, programming temperature and the SMR of unconstrained (stress-free) systems; thus, making it easier to decide between different SMP and to define the operative parameters in the useful life.

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Section: Mechanical Analysis: Influence Of the Network Structure And mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of the Network Structure and Programming Temperature on the Shape-Memory Response of Thiol-Epoxy “Click” Systems

et al. 2015

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“…370 First of all, as explained in our previous work [14], 371 the optimal mechanical point was found at T g E ', in 372 which both the stress and strain at break values were 373 enhanced, a physical effect called viscoelastic tough-374 ening [34,35]. Moreover, the values obtained are 375 higher than those reported by other authors with 376 epoxy-based systems, especially for the stress at 377 break (up to 55 MPa on the 3thiol-NEAT formulation 378 with 95 % of e b at T g E' ) [ 36,37]. On analysing the r-e 379 curves in Fig.…”

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confidence: 98%

New understanding of the shape-memory response in thiol-epoxy click systems: towards controlling the recovery process

2016

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Our research group has recently found excellent shape-memory response in “thiol-epoxy” thermosets obtained with click-chemistry. In this study, we use their well-designed, homogeneous and tailorable network structures to investigate parameters for better control of the shape-recovery process. We present a new methodology to analyse the shape-recovery process, enabling easy and efficient comparison of shape-memory experiments on the programming conditions. Shape-memory experiments at different programming conditions have been carried out to that end. Additionally, the programming process has been extensively analysed in uniaxial tensile experiments at different shape-memory testing temperatures. The results showed that the shape-memory response for a specific operational design can be optimized by choosing the correct programming conditions and accurately designing the network structure. When programming at a high temperature (T » Tg), under high network mobility conditions, high shape-recovery ratios and homogeneous shape-recovery processes are obtained for the network structure and the programmed strain level (eD). However, considerably lower stress and strain levels can be achieved. Meanwhile, when programming at temperatures lower than Tg, considerably higher stress and strain levels are attained but under low network mobility conditions. The shape-recovery process heavily depends on both the network structure and eD. Network relaxation occurs during the loading stage, resulting in a noticeable decrease in the shape-recovery rate as eD increases. Moreover, at a certain level of strain, permanent and non-recoverable deformations may occur, impeding the completion and modifying the whole path of the shape-recovery process.Postprint (author's final draft

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“…Due to their excellent thermomechanical properties, cross-linked epoxies are widely used as matrices for shape memory polymers [17][18][19]. Magnetic Fe 3 O 4 NPs dispersed in the epoxy matrix can be employed for the remote actuation of shape memory epoxies.…”

Section: Limiting Pips To a Local Scalementioning

confidence: 99%

Self-assembly of nanoparticles employing polymerization-induced phase separation

Williams

Hoppe

Zucchi

et al. 2014

Journal of Colloid and Interface Science

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Shape memory epoxies based on networks with chemical and physical crosslinks

Cited by 114 publications

References 27 publications

Effect of the Network Structure and Programming Temperature on the Shape-Memory Response of Thiol-Epoxy “Click” Systems

Effect of the Network Structure and Programming Temperature on the Shape-Memory Response of Thiol-Epoxy “Click” Systems

New understanding of the shape-memory response in thiol-epoxy click systems: towards controlling the recovery process

Self-assembly of nanoparticles employing polymerization-induced phase separation

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